The LIFE Picture Collection/Getty ImagesToday of course marks one of the most tragic days in rock history. Thirty-six years ago, John Lennon was murdered by Mark David Chapman outside of The Dakota, the New York City apartment building in which Lennon lived with his wife, Yoko Ono.

As she’s done many times before, Yoko’s using the anniversary of her husband’s murder to call attention to gun violence in America. Wednesday night, she tweeted the now-familiar image of the bloodied glasses Lennon was wearing when he was killed.

Together let’s bring back America the green land of PeaceThe death of a loved one is a hollowing experienceAfter 36yrs we still miss him pic.twitter.com/nRvdFKixW2